Cook 1/2 cup amaranth in 1 1/2 cups water in a covered saucepan over medium heat for 20 minutes until all water is absorbed and grains are fully tender. Let cool for 5 minutes. Meanwhile, stir together 1 tablespoon ground flaxseed and 3 tablespoons water in a small bowl; let sit for 5 minutes until gelled. In a large mixing bowl, combine the cooled amaranth, quinoa flakes, sliced scallions, green peas, flax egg, and a pinch of salt and pepper. Mix until evenly combined.

Divide the mixture into 3 equal portions and shape into patties about 3/4 inch (2cm) thick. If time allows, refrigerate the patties on a plate for 15–20 minutes — chilling firms them and makes flipping easier.

Heat 2 tablespoons olive oil in a non-stick skillet over medium heat until the oil shimmers. Carefully place the patties in the pan and cook for 5 minutes per side, undisturbed, until a golden-brown crust forms. Flip gently with a thin spatula.

In the same skillet, add the spinach leaves and sauté for 30–60 seconds over medium heat, tossing until just wilted. Season with a pinch of salt.

Cut the tomatoes into thin slices.

Toast the burger buns lightly if desired. Place a patty on each bun, top with wilted spinach and fresh tomato slices, and add your favourite condiments. Serve immediately.